[Q] boot.iimg,recovery.img

hello everyone!!
i am encountering a problem using nandroid backup! i changed my rom from stock to jasp next level! i make regular backups and on doing so in jasp i realised that the boot and recovery images are missing from my nandroid backup! it says install a patch file for a complete nandroid! the backup gets completed but i'm worried about the missing files! can anyone tell me about the use of those files and if they are important then how caan i restore them? will they cause a problem when i'll try to restore my nandroid backup? is this normal after changing to a custom rom from stock? please help me as i'm new to all of this!!

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